Embodiments of the inventive concept disclosed herein relate to semiconductor memory devices, and to methods of operating memory devices.
Semiconductor memory devices are classified into volatile semiconductor memory devices and nonvolatile semiconductor memory devices. The read and write speeds of the volatile memory device are fast, but when a power voltage supply is interrupted, data stored therein disappears. In contrast, even though power is interrupted, information stored in the nonvolatile semiconductor memory device does not disappear. Therefore, the nonvolatile semiconductor memory device stores information to be retained regardless of whether power is supplied.
A typical example of the volatile memory device may be a dynamic random access memory (DRAM) or a static RAM (SRAM). A typical example of the nonvolatile semiconductor memory device may be a flash memory device. The flash memory device is being used as a voice and image data storage medium of information devices such as a computer, a cellular phone, a smartphone, a personal digital assistant (PDA), a digital camera, a camcorder, a voice recorder, an MP3 player, a handheld PC, a game console, a facsimile, a scanner, and a printer. Nowadays, technologies for high-capacity, high-speed, and low-power nonvolatile memory devices are being researched to mount the nonvolatile memory device in mobile devices including a smartphone.
Technologies for guaranteeing data integrity are being continuously developed as the high-capacity, high-speed, and low-power technologies are being developed. In particular, there are attempts to increase a sensing margin of a sense amplifier in consideration of a relatively low driving voltage for low power.